Process of producing printing-plates.



lit

J n. eta v PROCESS OF PRODUCING PRINTING-PLATES.

Specification of Letters Patent.

Patented July 16, 1912.

oeasao- No Drawing.- Application filed October 5, 1911.- Serial No. 652,932.

T '0 all m it may concern:

Be is shown that l, Wnnznn Fm'sonn, a

subject of the German Empire, residing at Portland, in the county of Multnomah and State of Oregon, have invented new and useful Improvements in Processes of Producing Printing-Plates, of which the following is a specification.

In known processes for producing printing plates in which the developed picture is adapted to print, there is a particular difficulty to be overcome, viz: the picture pro duced through the developing in the sensitized layer is so influenced from the first coat of the. sensitized layer that the produced picture cannot retain the printing ink or again it may consist of a certain number a' dcsidcratum that the actinic and developed picture'shall he possessed of the capacity of receiving the printing ink. The tat repelling character is removed by dillerent proc esses for the production of printing plates, as: ']..--The surface of the plates is de oxidatedz'. 6., chemically treated. 2.The sensitized layer is mixed with an acid calcu 'lated to strongly act on the plates, the surface of the plates thus acted upon being removed by mechanical grinding of any suitable descriptiom 3.-The actinic and developed plates will-be made ready for printing through elcctro-galvanic treatment.

The object of my prcsentinvention is to provide a simple, economical and dtherwise advantageous process for producing printing plates of high grade.

In the practice of the invention the actinic printing plates will be exposed under the picture, and then developed. To make the printing plates susceptible for the printing ink, they will be coated with a peculiar fat 2'. 6., a fat containing an acid bound in ethereal oil. which the developed printing plates are coated changes the surface of the developed pictures in thescnsitizcd layer in such man nor that the printing plates will receive the printing ink without being subjected to a mechanical or a chemical action.

In. the carrying out of the process in the best manner of which I am cognizant, the printing 'plates'are first coated with a sensitizcd layer consisting of glue and bichrw mate. These coated plates are dried and exposed under the picture, and are then dovcloped in cold water, after which they age This 'fatty substance witlr dipped in a one per cent. solution of sodium hydroxid. After being given this bath the plates are thoroughly washed, and are then coated immediately with a fatty substance containing a corrosive-i. 0., an ethereal oil with those acids or their salts'which are proper for corrections. By this is meant that one design produced on a metal printing plate for lithographic printing is corrected, changed or amplified. For instance the design is increased in one part on the printing plate. This added portion of the design can be drawn on the printing plate with lithographic ink or lithographic pencil,-it being important to make the new drawn portion on the printing plate capable of receiving the printing ink before the produced design on the printing plate can be corrected, altered or amplified in its shape or corrected in any i'nanncr. The portion of the printing plate in which the changes or corrections are to be made inust be chemirally treated before the new design or any corrections can be made. The acids and salts for such treatments of printing plates for lithographic prints to make any correcand influenced that the corrected portion or new drawn design on the plate. is rendered capable of receiving printing ink. These acids and salts are always dili'erent according to the metals, and they are well known. Some of the ethereal oils have the property that they combine in certain percentage with acids or their salts. For instance, camphor or.oil of cloves is combined with acetic acid in about the proportions stated; viz: caniphor or oil of cloves 125 partsand acetic acid 15 parts to 1500 parts'of fat or any kind of printing inku If, the mixture of camphor or oil of clovcs and acetic acid be added to )rinting ink and the developed printing plates coatcd with the mixed fatty suhstance,ihe surface of the developed pictare-will he so atlccted and influenced that it is well adapted to receive and retain the printing ink. Thus the printing plates arecompleted and made ready for printing in one short operation. After coating the printing plates with the mixed fatty substance the surface of the developed picture in the sensitized layer is so afi'ected that the printing plate Will receive the printing ink Without being subjected to a mechanical or chemical action. Then after said coating and When the thin film of the sensitized layer is removed, the printing plate is adapted to receive any ,kind of printing ink to print from the plate. The actinic layer upon the plate and Which is fat repelling Without any etching, can he removed with a thin solution of sulfuric acid, but this is not absolutely necessary.

Having described my inventiony What .I

claim and desire to secure by Letters 1 st ent; is:

A process of producing photo-mechanic printing plates, which consists in coating the surface of a developed printing plate con taining a picture in a sensitized layer with nesses.

. l VENZEL FRITSCHE. lVitnesses PAUL /VAID'r, H. l/VING. 

